>I don't really see the issue?
The issue is that the instance you join dictates what "being a responsible member of the society" is, and if you don't fit into the restrictions of that one particular instance, you can lose your account which you use to interact with the entire federation.
Given that Mastodon admins can read direct messages of their users and ban them based on that, this is bound to have an effect on how users on Mastodon interact.
>There's also nothing preventing you from having multiple Mastodon accounts on multiple instances
Except for the fact that people use social networks like Twitter and Facebook to represent themselves. Which means one account. Having pseudonyms defeats the purpose.
In Mastodon, the model, in essence, makes you represent the instance you joined when you speak, with its values and restrictions — not yourself.
When deviance means loss of access, that's bound to result in increase in polarization and echo-chamberism.
Correspondingly, people who run instances block entire other instances based on how they perceive them.
This takes all the problems we have with email, and makes them worse.
"You can run your own instance" is an argument that works as well as "don't like Gmail? Host your own email server!".
I wouldn't have an issue if being banned from the instance you joined still allowed you to migrate to another instance after the ban without losing any data / identity / etc.
That's to say, if your identity wasn't tied to any particular instance.
Which is the point of the article.